Compass attachment.



No. 725,399. 'PATENTED APR. 14,1903.

L.'BLIss. COMPASS ATTACHMENT.

APPLICATION FILED APR. 18, 1902.

I0 MODEL.

1' rwenion g 6% THE NORRiS PETER8 cu, FHOTO-LITHQ. wmmcwr, n. c,

i To all whom it may concern:

I of the United States, and a resident of the borglass over the face ofa mariners compass UNITED STATES JOHN L. BLISS, 0F

NEW YORK, N. Y.

COM PASS ATTACHM ENT.

SPECIFICATION forming part of Letters Patent No. 725,399, dated April14, 1903.

Application filed April 18, 1902.

' Be it'k nown that I, JOHN L. BLISS, a citizen The object is to providea simple device which may be set on or removed from the and which willcast a true shadow on the face of the compass, so that the compassdirection and known direction of the sun from any point where theobservation is made may be compared without liability of error.

In the accompanying drawings, Figure 1 represents the instrument locatedon the face of the compass as in use. Fig. 2 is a top plan view of theattachment in detail, and Fig. 3 is a vertical section taken in theplane of the line 3 3 of Fig. 2.

The frame of the attachment consists of a base 1, having a generaltriangular form and provided near the three apexes with short legs 2,preferably faced with some suitable soft material-such, for example, asrubber or feltwhich will not be liable to scratch the glass over theface of the compass.

The base 1 is provided at its front with an uprising bracket, the legs 3and 4 of which gradually converge from the foot portions 5 and 6 to thehead portion 7, which latter portion is intended to span the centralaxis of the base 1. The uprising bracket is fastened to the base 1 bymeans of screws 8 and 9, which pass through the feet 5 and 6 into thebase.

The object of the uprising bracket is to sustain a thread 10 in a tautcondition between the base and the head 7 of the bracket. This isaccomplished as follows: The base is provided with a footpiece-'11,having an upwardly-projecting teat 12, which is intended to passupwardly through the base 1 at the middle point of the front of thebase, the said foot-piece 11 being also provided with a depending nipple13 for the purpose of centering the bracket in the glass plate. Thefootpiece 11 is provided with a perforation 14 of strains. 103,505. (Nomodel.)

tapered form, gradually growing smaller as it extends from the end ofthe nipple 13 upwardly through the foot-piece and teat 12 with a view ofclamping the end of the thread therein-as, for example, by tying a knotin the end of the thread or braiding its strands or otherwise enlargingthe end, so that it may be drawn within the larger part of the perforation, but cannot be drawn through the smaller part,

The head 7 of the bracket is provided with a perforation 15 in directalinement with the perforation 14 of the foot-piece 11 and has also athreaded perforation 16 a little distance The compass, or so much of itas is shown for the purpose of illustrating the practical operation ofthe attachment, is denoted by 19, its dial-plate by'20, and the glassover the face of the dial-plate by 21. The glass is provided directlyover the center of the dialplate with a conical or dished socket22, (seeFig. 3,) in which the nipple 13 on the footpiece 22 is received in orderto center the thread 10 directly in alinement with the vertical axis ofthe compass-plate.

In operation the attachment is placed on the glass plate of the compasswith the nipple 13 in the socket 22 and is then swung around by thefingers of the operator until the front of the attachment or thespirit-level lies transversely or about transversely to the direction inwhich the suns shadow will be cast. If the spirit-level does notindicate that the base of the attachment is level or in a truehorizontal position in a line transverse or about transverse to thedirection in which the by the sunlight across the face of the dial willi indicate by its position on the compass-dial the exact compassdirection of the sun, or, rather, the shadow will indicate the exactopposite of the compass direction of the sun, from which the exactcompass direction of the sun may be readily determined, and when thiscompass direction is compared with the true direction which the sun hasfrom the point where the observation is taken, as determined from thetables computed for this purpose, it will at once be evident how much orhow little the compass is in error, and the calculations for the courseof the vessel may be made with this error in view.

The gist of my invention lies in means for insuring the position of thatpart of the attachment which casts the shadow exactly at right angles tothe horizontal line transverse or substantially transverse to thedirection in which the shadow is to be cast and the means formaintaining this shadow-casting part at all times perfectly straight, sothat it shall cast a shadow which will truly indicate the compassposition of the sun.

By the structure above described the thread may be tightened wheneverfrom any cause it becomes slack by simply loosening the clampin -screw17, then exerting a pull on the end of the string which passes under thehead of the clamping-screw, and then tightening the said screw again. Anew thread may also be readily placed in position when the old onebecomes worn or frayed, and the attachment as a whole is extremelysimple in structure and accurate in operation.

What I claim is- 1. The combination with the glass plate of acompass-box provided with a socket in its upper face, of a compassattachment for determining the compass position of the sun,

the said attachment comprising a bracket provided with a projection forentering the socket in the glass plate of the compass-box to center thebracket with respect to the compass-plate, a thread extending from thebase to the head of the bracket, and means for permitting the adjustmentof the thread to render it taut.

2. A compass attachment for determining the compass position of the suncomprising a base, a bracket consisting of legs and a head, the legs ofthe bracket being arranged to gradually converge from the base to thehead, means for pivoting the base to the transparent plate of thecompass, a spirit-level on the base, a thread for castingashadow andmeans for permitting the adjustment of the thread to render it tautbetween the pivotal point of the base and the head of the bracket.

3. A compass attachment for determining the compass position of the suncomprising a base provided with feet, a bracket uprising from the baseand having legs extending from the base to a cross-head, a foot-piecelocated on the under side of the base and provided with a projection forpivoting the base to the glass plate of the compass, a thread forcasting a shadow, and means for permitting the adjustment of the threadto render it taut between the base and the head-piece, the saidfoot-piece forming, at the same time, a socket for the attachment of thethread.

In testimony that I claim the foregoing as my invention I have signed myname, in presence of two witnesses, this 26th day of March, 1902.

JOHN L. BLISS. Witnesses:

FREDK. HAYNES, HENRY THIEME.

